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Archive for the ‘Organic’ Category

A model for the single chirality of life

14 Nov 2011

The boiling solutions in prebiotic hot springs could shed light on the emergence of a single chiral form of biomolecules in nature, say Spanish scientists.

Amino acids and sugars exist in living organisms exclusively in one of their two molecular chiral forms, which are mirror images of one another. The reason for this specificity has long puzzled scientists. Conditions on Earth when life first evolved in prebiotic times presumably favoured one form over the other, but the mechanism is so far unresolved.

‘We will most likely be unable to solve this fascinating conundrum, but experiments carried out under environmentally credible conditions may be important signposts to this end,’ says Cristóbal Viedma at the Universidad Complutense, Madrid. With this in mind, he and colleague Pedro Cintas have investigated crystallisation processes that lead to single chiral forms.

Read the full news story in Chemistry World and download Viedma’s ChemComm communication to find out the exact details.

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50 days until 100 issues…

11 Nov 2011

….and did you know….?

Graphical abstract: Percent buried volume for phosphine and N-heterocyclic carbene ligands: steric properties in organometallic chemistry Steven Nolan’s Feature article from 2010 has received 50 citations to date according to Web of Science^SM (Thomson Reuters, 2011).

Read it: Percent buried volume for phosphine and N-heterocyclic carbene ligands: steric properties in organometallic chemistry

Are you interested in writing a Feature article? Contact the Editorial Office with your suggestion.

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Green hydrogenation of cyclic di-esters to diols

02 Nov 2011

Hydrogenation of esters under mild conditions is difficult at best, however David Milstein and his team push the boundaries by hydrogenating biomass products, glycolide and lactide, to afford the corresponding 1,2-diols. Their synthesis, which utilises ruthenium pincer complex catalysts, offers an atom-economical, green alternative to existing methods for producing 1,2-diols, which currently rely on petroleum-derived ethylene and propylene feedstocks.

The team say that the cyclic di-esters can be selectively and efficiently hydrogenated under very mild conditions, whilst producing no waste, and even discovered that optically pure diols could be produced from chiral lactide.

Download the ChemComm article today to find out how Milstein and his team did this.

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Aromaticity web theme issue – welcoming submissions

02 Nov 2011

We are delighted to announce a high-profile web themed issue on Aromaticity.

Guest editors: Nazario Martín (University Complutense of Madrid), Michael Hayley (University of Oregon) and Rik Tykwinski (University of Erlangen-Nuremberg)

This themed issue will consist of a series of invited Communications and Feature Articles covering work on all aspects of chemistry related with aromaticity – from new fundamental knowledge about aromaticity and theoretically interesting new arene structures to novel applications of aromatics and heteroaromatics which take advantage of their unique optical and electronic attributes.

The level of quality of this issue will be extremely high, and all manuscripts will undergo strict peer review. You are therefore encouraged to report work that you consider to be very important and conceptually significant. Please note that inclusion in the issue is subject to the discretion of the guest editors.

Publication of the peer-reviewed articles will occur without delay to ensure the timely dissemination of the work. The articles will then be assembled on the ChemComm website as a web-based thematic issue.

Submit your work before 31^st May 2012. Please add “aromaticity” in the comments to the editor section.

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Metal evasion still leads to nitration

31 Oct 2011

Researchers from Germany and China have designed a simple method for forming nitroarenes.

Aromatics substituted with nitro groups are ubiquitous motifs in important molecules required by the textiles, materials and pharmaceutical industries.

However, installing nitro groups can be tricky because it requires the use of strong acids or dinitrogen peroxide. These harsh conditions are not commonly tolerated by sensitive functionality present in molecules, and problems of selectivity or over-nitration commonly arise. Alternate methods use large quantities of silver salts or expensive palladium catalysts.

Now Xiao-Feng Wu (Zhejiang Sci-Tech University, China), Matthias Beller (Leibniz Institute for Catalysis, Germany) and colleagues have designed a metal-free method for nitrating aryl boronic acids.

The team used an alkyl nitrite at 80 ˚C to convert the boronic acid group to a nitro group. The reaction works in moderate to good yields for electron-rich and electron-neutral aryl boronic acids. Electron-poor aromatics are more challenging substrates, as the boronic acid are less reactive.

While this method is not yet suitable for vinyl or hydroxy substituted aryl boronic acids, it offers an economically and operationally attractive method for synthesising nitro compounds.

Researcher’s perspective:Our initial investigations started with the use of a rhodium catalyst, because of rhodium’s known ability to transmetalate with arylboronic acid. Our target product, nitrobenzene, was formed but we found that the rhodium catalyst is not necessary for this transformation.

On one hand, we were disappointed, as our aim is to develop catalytic reactions; on the other hand, we are happy, because this reaction works so nicely.

Xiao-Feng Wu

Using this method, nitroarenes can be easily prepared from arylboronic acids without using catalyst and hazardous reagents.

More information can be found in the ChemComm communication, free to download for a limited period.

Posted on behalf of Alice E. Williamson, ChemComm web writer.

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Ionic Liquids web theme issue – welcoming submissions

03 Oct 2011

ChemComm is delighted to announce a high-profile web themed issue on Ionic Liquids.

Guest editors: Robin D. Rogers (University of Alabama), Doug MacFarlane (Monash University) and Suojiang Zhang (Institute of Process Engineering)

Picture courtesy of Photodisc

This issue will consist of a series of Communications and Feature Articles from prominent scientists working on all aspects of ionic liquid chemistry. The scope will range from new fundamental knowledge about ionic liquids to novel applications of ionic liquids which take advantage of their unique attributes. Follow on studies or those of routine interest will not be considered.

The level of quality of this issue will be extremely high, and all manuscripts will undergo strict peer review. You are therefore encouraged to report work that you consider to be very important and conceptually significant in accord with the ChemComm mandate. Please note that inclusion in the issue is subject to the discretion of the guest editors.

Submit your work before 29^th February 2012. Please add “ionic liquids” in the comments to the editor section.

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Carbonic anhydrase inhibitors

29 Sep 2011

New drugs need to be found that are capable of targeting carbonic anhydrases – a class of enzyme that catalyses the hydration of carbon dixoide to bicarbonate and H⁺. By inhibiting or activating these enzymes, a number of pathological disorders can be treated such as glaucoma, osteoporosis and cancer. Unfortunately, many of the drugs developed so far are not selective for the different isoforms of the enzyme.

Representation of the binding mode of an inhibitor compound in the active site cavity of the enzyme

Researchers from Italy have embarked upon investigating the inhibition of mammalian isoforms of carbonic anhydrase using N-substituted benzenesulfonamides. By employing X-ray crystallographic studies, they discovered a completely new binding mode with the enzyme. The team say that by substituting the moieties on the phenyl ring, unexplored regions of the enzyme active site could be targeted, allowing new lead compounds to be identified.

Read the ChemComm article to learn more about their findings.

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Ginkgo biloba extract used to make Tamiflu

25 Aug 2011

Graphical abstract: Extraction and isolation of shikimic acid from Ginkgo biloba leaves utilizing an ionic liquid that dissolves cellulose A new way of obtaining shikimic acid, the compound needed to make Tamiflu, has been discovered. Shikimic acid is normally obtained from star anise, a Chinese cooking spice. The shortage of star anise caused Roche problems a few years ago, when the demand for Tamiflu peaked during the H1N1 pandemic in 2009, so new sources are constantly being sought.

Toyonobu Usuki, from Sophia University, Tokyo, found that shikimic acid could be isolated from ginkgo biloba leaves using an ionic liquid. Ginkgo biloba is a tree mainly found in China and has often been used in Chinese medicine.

Find out more – read Usuki’s ChemComm communication.

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Sugar injection to beat hospital infection

18 Aug 2011

Bacteria A carbohydrate from the surface of the most virulent strain of the bacterium Clostridium difficile has been synthesised by chemists in Germany. The molecule could be used to develop a vaccine against the infection.

C. difficile infections are the most common cause of hospital acquired diarrhoea and can lead to the death of elderly patients and those with weakened immune systems.’C. difficile is on the rise in industrialised countries,’ says Peter Seeberger, who led the team that carried out the research at the Max Planck Institute of Colloids and Interfaces, Potsdam. ‘There is a need for a vaccine but it’s a big challenge.’

Find out more about Seeberger’s progress towards developing a vaccine in the full Chemistry World news story and download his ChemComm communication, free for a limited period.

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The first hydroamination reaction with a zincocene complex

20 Jul 2011

Peter Roesky, Siegfried Blechert and co-workers at the Karlsruhe Institute of Technology and the Berlin University of Technology have reported the first use of a dizinc complex as the catalyst in a hydroamination reaction.

Hydroamination is the addition of an N–H bond of an amine to an unsaturated C–C bond to give a molecule that contains nitrogen in one step. This is particularly important because many current amine syntheses are multi-step processes. Zinc complexes are advantageous for hydroamination as they are relatively cheap, air and moisture stable and tolerant to a wide variety of functional groups.

With this in mind Roesky and Blechert decided to test the zincocene complex, Zn₂(η⁵-C₅Me₅)₂, for its hydroamination activity. This complex was discovered in 2004 but it is the first time that it has been used as a catalyst. The team found that the catalyst worked well with good yields and conversions and that it tolerates many functional groups.

Want to find out more? Then download the ChemComm article for free today and leave a comment below.

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